Pin mixer



June 9, 1953 R. R. TEALE ,6 5

PIN MIXER Filed April 21 1951 INVENTOR.

Patented June 9, 1953 UNITED STATES OFFICE PIN 4 Robert R.-'1?eale-, sn'y'uer, N. Y., assigndr' to' Na tiorial Gyiisu'fii -company; B'ufia'lm -Nl Y. Application Aprii 21, 1951.Serial N o; 2221110 This invention relates" to mixers and refers particularly to mixers for preparing slurries of cementitious materials The principles of the mixer of the presentinven'tion may be applied in mixing various materials, but its advantages are particularly evident in preparing slurries for the manufacture of gypsum products, and its constructionjand op"- eration will accordinglybe discussed herein" as applied to the mixing of calcined ypsum or stucco and water to form a slurry of gypsum plaster.

The principles of the present invention are particularly adaptable to mixers of the type known in the art as pin mixers wherein the mixer is' in the form of a relatively fiat cylinder mounted on a vertical axis with the materials moving through the mixer as a combined result of the force of gravity and centrifugal'for'ce and discharging near an edge or peripheral portion of the mixer casing. In such mixers it is customary to introduce the calcined gypsum or stucco and the water at different points located somewhat in the vicinity of the center of the mixer, but conventional construction is such that it isusual to have these two feed entrances disposed separately and each located eccentrically of the center of the mixing chamber and eccentrically of the axis of rotation of the mixing rotor.

, Ordinarily the shaft of the mixing rotor and its supporting bearings require that the separate entrance orifices for gypsum and water be located at points spaced from the central region of the mixer. This design and construction, while generally conventional in this art, results in certain undesirable unevenness and inequal-' ity in mixing results, since the radial path from the point where the gypsum is introduced to the periphery of the mixer is unequal in various directions, the radial path from the point where the water is introduced to the periphery of the mixer in various directions is unequal, and the paths of the two materials are not the same invarious directions.

The mixer of the present invention is so arranged and constructed that it is possibleto introduce both the calcined gypsum or stucco-and the water centrally of the mixer and in such a" way'that their paths and the lengths of their paths in all radial directions to the periphery of the mixer are entirely uniform. Further, this arrangement results in all of the calcined gypsum v or stucco being supplied with water atthe same distance from the axis of the mixer andre'sults 7 Claims. (01-; 259 8) 2* all of the calcined gfyipsunib'eii'igsupplied with absolutely uniform rel'ativ quantities"or water? 1 the embodiment of theiiiiiefitioli, WIii'chiis setfbitlfindetailhereirfb3 way of example, this result is effected by introducing the" calcined gypsum in an annular flow concentric with the axis of the mixer", the" water being" introduced centrauy Within such" annulus" and by: means Of a" conduit likewise" concentric with" the" axis" Of themixer.

Various mechanical modifications of the mixer may be made without departing from the principles" 0'1" themes-emf invention; A single Spell iile" embodiment is illustrated in: the" drawings and described herein" mere1y" wayfexamme' but the present, invention is" lii nited thereto or otherwise excepting a's" definedin the append: ed claims.

Fig; 1 is a top plan view; partly in arose-sec: tion, of oneforrmof them'ixer' of the presentin vention; and

Fig. 2 is adongitudiiial cross-sectional View 011 a somewhat iargr scale" and taken On" the" line IIII of Fig. 1.

Like characters of refere'nce denot'e-lile parts, and the numeral Hi" designates generally" a flat cylindrical casingh'avihga radial botterii' wall H and-a circularside-wall i2 1 A co'v'er elementIt completes the casing and is provided with a nun'ib'e'r or concentnc circuiar seriesorstationary depending pin's l4; 7

ilh'e' l'r'iixirig" 're'tr. 'rcomprises-generally a fla't disc I5 having a? mounting slfaft" portion I 6 which may passthrough stuflin'g 'b'o'x or packing ar ranger nent I! in the radial b'ott'emw'all H of casing element l0',lalthough there is-ne'ce'ssityfor a packed joint or a tight mat the point where the rotor shaft l6 passes downwardly through I The" manner which the shaftlB is mounted for driving-rota? bottom wall H of the casing.

tio'n' an'd the manner in which it' is driven form no part of the novel structure o'f'the pre's'entin vention' and accordingly needn'ot be illustrated '01- described;

Wardlybetween the circular rows of' pins M as appears clearlyin- Fig2 2:

'Ilhefcovef mem er [3 of tlie mixing chamber is' -pro'vided with a central conduit 20' for intr'o duc'ing I a downward new of" dry calcined gypsum in any desired manner, and its terminal portion extends downwardly centrally of the mixer and centrally of conduit 20 as at 22 in Fig. 2. The terminal portion 22 of water conduit 2| preferably extends down to a point fairly close to the top surface of rotor [5, so that water is forced therefrom uniformly in all radial directions.

A separating sleeve which is likewise coaxial with the conduit 20 and with the axis of rotor I5 is mounted fixedly on a plate 26, which, in turn, is secured to rotor I5 as by means of a plurality of studs 21. A cap 28 extends over the upper end of sleeve 25 and in the illustrated instance is fixed to the downwardly extending portion 22 of the water inlet conduit.

Cap 28 is provided with an annular depending flange which extends downwardly over the upper end of sleeve 25, so that cap 28 and sleeve 25 serve to isolate the flow of calcined gypsum or stucco and the fiow of water until the water passes beneath plate 26 and reaches the inner-. most circular series of the mixing'pins. However, cap 28 and sleeve 25 are out of contact so that free rotation of sleeve 25 relative to the cap is not interfered with.

Preferably an upstanding circular series of pins 30 is carried by plate 28 and extends upwardly in the space between sleeve 25 and gypsum conduit 20, the pins serving to keep the incoming calcined gypsum or stucco in a loose and clear flowing condition.

The flow of mixing water and gypsum from the center of the mixer toward the periphery is thus entirely uniform in various directions about the mixer both as to quantity and proportions and the rate of flow is substantially uniform because of these equal values and the uniform centrifugal force on the materials. The material, after passing radially beyond the various intermeshing mixing pins l4 and [8, may be discharged in any desirable manner and at any number of points around the periphery of the mixer. In the present instance, and by way of example only, a discharge spout is designated 3| in Figs. 1 and 2.

In the foregoing specification and the following claims the terms pin mixer and mixing pins are employed and the pins l4 and I8 are shown as being of circular cross-section. However, it is to be understood that the term "pin" is used in a generic sense, and that the pins or bars may be of square or rectangular crosssection or otherwise, that various combinations of pins and bars may be employed, and that the claims are to be construed in that light.

What is claimed is:

1. In a pin mixer, a generally cylindrical casing having a vertical axis and radially extending top and bottom walls, a plurality of stationary mixing pins projecting downwardly from the top wall of said casing, a discoidal rotorin said casing having a plurality of upwardly projecting mixing pins, located so as to pass between the stationary mixing pins upon rotation of said rotor, rotary drive means at the under side of said rotor, an inlet conduit communicating with said mixer concentrically through said top wall, and a second conduit extending within said first conduit centrally thereof and downwardly in said mixer substantially below the lower end of the first conduit, sleeve means carried by said rotor with its lower end adjacent to the lower end of said second conduit and extending upwardly between said conduits concentrically and spaced radially from both, conduits, and a concentric cap carried by said second conduit and extending over the upper end of said sleeve means, whereby said cap and said sleeve means insure isolation of thematerials of the two conduits until they merge in the mixing chamber.

2. In a pin mixer, a generally cylindrical casing having a vertical axis and radially extending top and bottom walls, a plurality of stationary mixing pins projecting downwardly from the top wall of said casing, a discoidal rotor in said casing having a plurality of upwardly projecting mixing pins, located so as to pass between the stationary mixing pins upon rotation of said rotor, rotary drive means at the under side of said rotor, an inlet conduit communicating with said mixer concentrically through said top wall, and a second conduit extending within said first conduit centrally thereof and downwardly into said mixer whereby both conduits discharge material uniformly coaxially in said chamber, sleeve means carried by said rotor with its lower end adjacent to the lower end of said second conduit and extending upwardly between said conduits concentrically and spaced radially from both conduits, and a concentric cap carried by said second conduit and extending over the upper end of said sleeve means, whereby said cap and said sleeve means insure isolation of the materials of the two conduits until they merge in the mixing chamber.

3. In a mixing device, a casing forming an annular mixing chamber, a discoidal rotor therein having a substantially vertical axis, rotary drive means at the under side of said rotor, an inlet conduit disposed above said casing and communicating with said mixing chamber centrally thereof through the upper wall of said chamber, and a second inlet conduit extending downwardly into said mixing chamber within said first conduit and centrally thereof, said second conduit extending downwardly in said casing substantially beyond the lower end of said first conduit, sleeve means carried by said rotor with its lower end adjacent to the lower end of said second conduit and extending upwardly between said conduits concentrically and spaced radially from both conduits, and a concentric cap 7 carried by said second conduit and extending over the upper end of said sleeve means, whereby said cap and said sleeve means insure isolation of the materials of the two conduits until they merge in the mixing chamber.

4. In a mixing device, a casing forming an annular mixing chamber, a discoidal rotor therein having a substantially vertical axis, rotary drive means at the under side of said rotor, an inlet conduit disposed above said casing and communicating with said mixing chamber centrally thereof through the upper wall of said chamber,

and a second inlet conduit extending downwardly into said mixing chamber within said first conduit and centrally thereof, whereby both conduits discharge material uniformly coaxially in said chamber, sleeve means carried by said rotor with its lower end adjacent to the lower end of said second conduit and extending upwardly between said conduits concentrically and spaced radially from both conduits, and a concentric cap.

carried by said second conduit and extending over the upper end of said sleeve means, whereby said cap and said sleeve means insure isolation of the materials of the two conduits until they merge in the mixing chamber.

nular mixing chamber, a discoidal rotor therein having a substantially vertical axis, rotary drive means at the under side of said rotor, an inlet conduit disposed above said casing and communicating with said mixing chamber centrally thereof through the upper wall of said chamber, and a second inlet conduit extending downwardly into said mixing chamber within said first conduit and centrally thereof, whereby both conduits discharge material uniformly coaxially in said chamber, an annular plate extending about said second conduit and underlying the discharge portion of the first conduit, whereby material feeding into the mixing chamber from said first conduit moves radially outwardly above said annular plate and the material feeding into the mixing chamber from said second conduit moves radially outwardly below said plate and the two materials commingle only after passing radially outwardly beyond said plate.

6. In a mixing device, an annular mixing chamber, a discoidal rotor in said chamber, a drive shaft for said rotor fixed concentrically thereto and extending downwardly out of said chamber and a pair of coaxial conduits of different diameter communicating with the upper wall of said chamber concentrically thereof for introducing a plurality of ingredients by coaxial concentric downward flow, an annular plate surrounding the lower end of the inner of said conduits and spaced below the lower end of the outer of said conduits whereby material feeding into the mixing chamber through the inner conduit moves radially outwardly beneath said annular plate and material feeding into the mixing chamber through the outer of said conduits moves radially outwardly above said annular plate and the respective materials commingle only after passing radially outwardly beyond said plate.

7. In a mixing device, a casing forming an annular mixing chamber, a discoidal rotor therein' having a substantially vertical axis, rotary drive means at the under side of said rotor, an inlet conduit disposed above said casing and communicating with said mixing chamber centrally thereof through the upper wall of said chamber, and a second inlet conduit extending downwardly into said mixing chamber within said first conduit and centrally thereof, whereby both conduits discharge material uniformly coaxially in said chamber, means extending about said second conduit and including an annular plate underlying the discharge portion of the first conduit, whereby material feeding into the mixing chamber from said first conduit moves radially outwardly above said annular plate and material feeding into the mixing chamber from said second conduit moves radially outwardly below said plate and the two materials commingle onlyafter passing radially outwardly beyond said plate.

ROBERT R. TEALE.

References Cited in the file of this patent UNITED STATES PATENTS- 

